1. Field of the Invention
An aspect of the present invention relates to portable cutting machines and, in particular, to a portable cutting machine adjustable in cutting depth.
2. Description of the Related Art
There have conventionally been portable cutting machines achieved by making cutting machines portable for cutting and processing to-be-processed members such as lumber. Such portable cutting machines, which consist mainly of a circular saw blade and a motor as a drive unit, are easily taken anywhere and thus used generally not only in manufacturing plants but also at construction sites and the like.
Since lumber to be cut by portable cutting machines has respective different thicknesses, it is necessary that various types of boards, from thick to thin boards, can be cut suitably. Conventional portable cutting machines are arranged in such a manner that a saw cover or a housing on which a circular saw blade is supported is rotatable with respect to a base to be brought into contact with lumber and the amount of rotation thereof determines the amount of protrusion of the circular saw blade from the base.
For example, in the portable cutting machine 901 shown in FIGS. 12A and 12B, the saw cover 904 covering the circular saw blade 903 is supported rotatably centering on the support part 961 with respect to the base 906. The movement restricting part 905 connected with the saw cover 904 is adapted to slide along the link 907 to cause the saw cover 904 on which the circular saw blade 903 is supported to be rotated with respect to the base 906 and thereby the amount of protrusion of the circular saw blade 903 to be changed. Specifically, the movement restricting part 905 moves upward along the path indicated by the broken line B so that the amount of protrusion of the circular saw blade 903 decreases. In the drawings, the broken line B forms a circular arc with a radius of R centering on the support part 961, where R represents the distance from the support part 961 to the point where the movement restricting part 905 and the link 907 are in contact with each other. Therefore, the link 907 is fixed to the saw cover 904 on the broken line B by the movement restricting part 905.
However, forming the link 907 along the broken line B causes the saw cover 904 that covers the link 907 to grow in size. Hence, the link 907 may be formed by an elastic thin plate in such a manner as to be housed in the saw cover 904 as shown in FIG. 12A. In this arrangement, the higher the movement restricting part 905 is positioned, the greater the tensile force required to arrange the link 907 on the broken line B, resulting in a problem of difficulty in movement of the movement restricting part 905.
Hence, the portable cutting machine disclosed in JP-UM-H03-29221-A is provided with a dust case connected with a saw cover to prevent chips from attaching to the link by sucking chips from the saw cover into the dust case.
However, the arrangement disclosed in JP-UM-H03-29221-A has a high possibility that chips are not sucked completely due to, for example, reduction in the suction power of the dust case. Leftover chips will attach to the link to become resistance when the movement restricting part slides, resulting in a reduction in the operating efficiency.